1 00:00:00,540 --> 00:00:07,350 What you'll notice is spending tree convergence is very quick and that's because we running rapid pivot 2 00:00:07,380 --> 00:00:07,980 plus. 3 00:00:09,320 --> 00:00:11,750 I didn't make any changes on these switches. 4 00:00:11,840 --> 00:00:13,550 From a spending tree point of view. 5 00:00:15,920 --> 00:00:21,110 So the command show run pipe include span shows the default config. 6 00:00:22,770 --> 00:00:25,880 And notice the spanning tree used is rapid pivot. 7 00:00:26,460 --> 00:00:33,810 In the output it shows as always PTP or rapid spanning tree but this is actually rapid per VLAN spanning 8 00:00:33,840 --> 00:00:34,320 tree. 9 00:00:34,710 --> 00:00:38,640 We can change the mode of spanning tree. 10 00:00:38,640 --> 00:00:44,130 But before I do that, just to make the point again at the moment. 11 00:00:44,870 --> 00:00:52,490 Show spanning tree on switch three shows that the root port is gigabit zero one the sport. 12 00:00:53,060 --> 00:00:56,090 If I shut that port down. 13 00:00:59,090 --> 00:01:01,670 And then top shows spanning tree again. 14 00:01:01,880 --> 00:01:06,230 What you'll notice is gigabit is zero, zero is the root put. 15 00:01:07,370 --> 00:01:12,290 Convergence is very quick with rapid spending because it doesn't use timers. 16 00:01:15,660 --> 00:01:20,610 So the max age and for delayed timers are not used for convergence. 17 00:01:20,970 --> 00:01:26,460 The switches send messages to each other with rapid spanning tree to enable quick convergence. 18 00:01:26,790 --> 00:01:35,580 So now if we change the spanning tree type or mode to PV ist, we should see that spanning tree takes 19 00:01:35,580 --> 00:01:37,500 a lot longer to converge. 20 00:01:38,890 --> 00:01:41,410 So I'll change that on all switches. 21 00:01:45,030 --> 00:01:46,170 Switch three. 22 00:01:47,650 --> 00:01:48,880 Switch for. 23 00:01:55,070 --> 00:01:56,180 Switch five. 24 00:02:00,020 --> 00:02:08,389 So back on switch three show spanning tree notice we can see that the switch is still learning which 25 00:02:08,389 --> 00:02:12,290 ports are the root port, designated port or blocking port. 26 00:02:12,500 --> 00:02:17,390 When in the learning state traffic will be blocked. 27 00:02:17,810 --> 00:02:22,460 User traffic will only be forwarded when ports transition to the forwarding state. 28 00:02:23,540 --> 00:02:28,760 At the moment you can see that the spanning tree protocol used or shown here is triple E. 29 00:02:28,910 --> 00:02:35,750 But once again, you need to be careful because on Cisco switches, even though it displays triple E, 30 00:02:35,780 --> 00:02:40,760 we actually using PVS, DT PVS, RT is once again backward compatible. 31 00:02:40,760 --> 00:02:48,560 So it will be able to talk to an 802.1 DX switch from another vendor as an example, so we can see triple 32 00:02:48,590 --> 00:02:50,150 E in the output here. 33 00:02:51,590 --> 00:02:54,230 So once again show spanning tree. 34 00:02:54,710 --> 00:02:58,070 The root port in this case is now gigabit zero zero. 35 00:03:00,800 --> 00:03:01,780 So what happened? 36 00:03:01,790 --> 00:03:05,120 Because previously we had switched one as the route. 37 00:03:08,300 --> 00:03:09,710 It still has a command. 38 00:03:12,170 --> 00:03:19,820 Show spending tree shows us that the switch is the root of the topology, but gigabit zero one is not 39 00:03:19,820 --> 00:03:21,080 shown in the output here. 40 00:03:21,950 --> 00:03:22,910 Because I need to know. 41 00:03:22,910 --> 00:03:24,200 Shut that port. 42 00:03:24,350 --> 00:03:24,710 So. 43 00:03:24,710 --> 00:03:25,730 Confetti. 44 00:03:25,820 --> 00:03:26,810 Interface gigabit. 45 00:03:26,840 --> 00:03:27,710 Zero one. 46 00:03:27,980 --> 00:03:31,400 No shut show spending tree. 47 00:03:32,810 --> 00:03:35,630 Notice that port is a listing port. 48 00:03:36,780 --> 00:03:39,480 Gigabit zero zero is a blocking port. 49 00:03:39,600 --> 00:03:42,780 So this port is blocking this port is listening. 50 00:03:45,230 --> 00:03:49,670 And what you'll notice is it'll take it a while to converge. 51 00:03:49,700 --> 00:03:51,500 I'll put an IP address on the switch. 52 00:03:52,950 --> 00:03:55,650 We'll be waiting and then I'll demonstrate this again. 53 00:04:00,810 --> 00:04:03,420 Put an IP address on switch one. 54 00:04:14,300 --> 00:04:15,950 While no shut the interface. 55 00:04:17,130 --> 00:04:23,100 So paying 10.1 did 1 to 1 camping itself. 56 00:04:24,010 --> 00:04:25,090 Switch three. 57 00:04:25,480 --> 00:04:25,680 No. 58 00:04:25,690 --> 00:04:29,710 Shut the interface paying ten .1. 1 to 1. 59 00:04:31,310 --> 00:04:33,230 Ping succeeds, so I'll just do that again. 60 00:04:33,650 --> 00:04:36,860 Notice the ping from switch three to switch one succeeds. 61 00:04:37,580 --> 00:04:45,620 Show spanning tree convergence has taken place because gigabit zero one is the root port and is forwarding. 62 00:04:46,760 --> 00:04:53,000 But now if I shut down gigabit zero one and then try and ping switch one. 63 00:04:55,060 --> 00:05:03,220 The port has gone down, but pings are failing even though we have a redundant link show spanning tree 64 00:05:03,220 --> 00:05:06,130 shows me that the root port is still learning. 65 00:05:08,350 --> 00:05:11,500 Still learning pings fail. 66 00:05:12,340 --> 00:05:15,580 PV ist takes a long time to converge. 67 00:05:16,090 --> 00:05:19,000 Can take 30 seconds for that convergence to take place. 68 00:05:19,570 --> 00:05:21,520 As you can see there, it's just happened. 69 00:05:21,910 --> 00:05:26,470 Show spanning tree shows us now that gigabit zero one is forwarding. 70 00:05:28,350 --> 00:05:38,100 But once again if I know shut gigabit zero one and did the ping again the ping would fail because it 71 00:05:38,100 --> 00:05:40,920 now needs to learn that this is the better path. 72 00:05:41,250 --> 00:05:48,510 So spending tree notice the root port gigabit zero one is in the listening state. 73 00:05:49,410 --> 00:05:57,360 So we have listening, then we have learning and after a while it should go to forwarding. 74 00:05:57,360 --> 00:05:59,670 But that can take 30 seconds. 75 00:06:00,150 --> 00:06:01,530 So it's still learning. 76 00:06:01,830 --> 00:06:06,630 Now it's gone to forwarding and now pings will succeed. 77 00:06:07,050 --> 00:06:11,220 So ports have different states in a blocking state. 78 00:06:11,250 --> 00:06:13,540 User traffic is not forwarded. 79 00:06:13,560 --> 00:06:17,670 The switch doesn't learn MAC addresses based on frames received. 80 00:06:17,940 --> 00:06:20,310 This is a stable state for a port. 81 00:06:20,670 --> 00:06:22,380 A listening and learning port. 82 00:06:22,380 --> 00:06:24,390 Do not afford frames either. 83 00:06:24,750 --> 00:06:29,420 Listing ports don't learn MAC addresses based on frames received. 84 00:06:29,430 --> 00:06:32,130 In other words, they don't update the MAC address table. 85 00:06:32,160 --> 00:06:35,430 A learning port does update the MAC address table. 86 00:06:35,820 --> 00:06:39,960 This is a temporary state or transitionary state. 87 00:06:40,260 --> 00:06:46,560 While the switches learn the topology in a forwarding state, frames are forwarded, MAC addresses are 88 00:06:46,560 --> 00:06:49,500 learnt and this is a stable state. 89 00:06:49,590 --> 00:06:52,230 In other words, this is not a transitionary state. 90 00:06:52,350 --> 00:06:56,580 The state will stay that way until there's a change in the topology. 91 00:06:56,790 --> 00:07:02,280 A disabled port doesn't receive frames, doesn't forward frames, doesn't learn about Mac addresses 92 00:07:02,280 --> 00:07:07,350 on a port, and this port will stay in that state until you enable the port. 93 00:07:07,860 --> 00:07:16,770 Now, if we change that to rapid spanning tree, so spanning tree mode, rapid pivot, what we should 94 00:07:16,770 --> 00:07:19,980 notice is that convergence takes place a lot quicker. 95 00:07:20,640 --> 00:07:25,830 I'll only enable rapid spanning tree on switch one, two and three. 96 00:07:28,140 --> 00:07:29,550 Show spending tree. 97 00:07:31,260 --> 00:07:32,910 Rather show spanning tree. 98 00:07:34,780 --> 00:07:39,820 Shows us that the spending tree mode now enabled is rapid per VLAN spanning tree. 99 00:07:40,810 --> 00:07:42,910 We've got a path cost using gigabit. 100 00:07:43,030 --> 00:07:43,930 Zero one. 101 00:07:44,230 --> 00:07:47,160 So as you can see, gigabit zero one is the route port. 102 00:07:51,420 --> 00:07:51,840 The switch. 103 00:07:51,840 --> 00:07:53,070 Camping switch one. 104 00:07:53,910 --> 00:07:54,990 I'll shut. 105 00:07:56,040 --> 00:07:57,480 That put down. 106 00:07:59,790 --> 00:08:06,840 And when we do a ping again, it instantly can ping switch one even though we've just seen the interface 107 00:08:06,840 --> 00:08:14,070 go down in the output here because spanning tree converges a lot quicker when using a rapid spanning 108 00:08:14,100 --> 00:08:14,580 tree. 109 00:08:14,880 --> 00:08:22,470 So the moral of the story is that in the real world you want to use a rapid pivot rather than PV ist.